The 1906 San Francisco Earthquake
—Chrissie

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            The geology and geography of the west coast of North America are made of crust and stone that was added onto the continent by the collision of the Pacific and North American plates about thirty million years ago. These two plates now scrape past each other at the San Andreas Fault at a rate of about ten centimeters (or 4-5 inches) per year. This achingly slow pace is an average, however; there can be long stretches of time during which the two plates move very little, because they are “stuck” somewhere along the line. When they become unstuck, there is an abrupt movement in which all of the built-up energy is released, an earthquake. One of the most devastating earthquakes in American history was caused by such movement on the morning of 18 April 1906. A little after five am, 296 miles (477 km) of the San Andreas fault moved, rocking northern California with a quake estimated at between 7.9 and 8.3 on the Richter Scale (estimated years later, because that scale had not yet been established). While the quake itself was severe, completely destroying buildings and neighborhoods, fires caused by broken gas lines, which could not be put out because of broken water lines, caused more damage.

            Over the decades previous, the population of San Francisco had grown exponentially, prompting rushes of construction that paid little attention to safety. The tightly packed streets, ramshackle buildings, and development on unstable terrain was the perfect recipe for disaster. It was made worse by the fact that the city had experienced a devastating fire five decades earlier but seemed to have learned nothing from it. There were few regulations about where and how buildings could be constructed or what materials could be used.

            The quake had been foreshadowed by small quakes over the previous few days, but such things were not at all unusual in California, and so caused little concern. Then, at 5:12 am on the 18th there was a foreshock that lasted between fifteen and twenty seconds. A few moments later the main quake began, lasting an interminable forty-two seconds. This caused shaking as far north as central Oregon, as far south as Los Angeles, and as far east as central Nevada. Aftershocks continued for days, some of them branching out on faults connected to the San Andreas as the earth resettled all along the plate boundaries. The immediate death count is estimated at about five hundred people, but the total for the entire disaster is believed to be at least three thousand. Most of these were in San Francisco and were not caused by the quake itself but by its aftereffects: fires, disease-tainted water, and the delayed collapse of buildings. An estimated 250,000 people were left homeless. 

            The damage that was a direct result of the quake was seemingly random; some buildings had simply collapsed from the shaking while others were damaged but intact. This was due primarily to the materials used in construction and the location. Some areas of the city had been built on loose fill and sand which separated during the quake in a process called liquefaction. The structures in these locations collapsed as the earth below them flowed like water. The movements destroyed not only structures above ground, but underground systems as well, most importantly natural gas and water pipes. Either of these alone had the potential to be devastating in an emergency, but both together created a situation by which fires were being fed endlessly by the gas anywhere there was a rupture while water could not be directed where it was needed to put out the fires. In an additional cruel irony, Fire Chief Dennis Sullivan was killed in the initial shaking by a chimney that fell onto the fire station where he was asleep. City Hall was also destroyed in the initial quake, a victim of both liquefaction and shoddy workmanship.

            The nearby Army and Navy bases meant that soldiers who could render aid were nearby. It was they who saved a great deal of the city from the fire by arranging for water to be pumped from the bay to hoses that were applied to the fires near the waterfront and filled firetrucks for use elsewhere. Even with this assistance, the fires burned out of control. In a last-ditch attempt to slow and stop the burning, buildings were destroyed with dynamite to create firebreaks; they only added to the flames. In the end it took four days to extinguish the flames. The Army also organized shelter, food, and clean drinking water for those rendered homeless.

The worst-hit population was likely those in Chinatown. We cannot be sure how many people were killed there; the census records from 1900 indicated about 11,000 people, but by 1906 it is believed to have been closer to 25,000. A great deal of the community was destroyed, but this offered an unusual opportunity in rebuilding: a Chinese business owner named Look Tin Eli arranged for the area to be rebuilt with stereotypically Asian features like pagodas and decorated in a similar style. This had the effect of turning what had essentially been a slum into a popular tourist attraction. The immigrant inhabitants of the area also benefitted from the disaster because almost all of the city records were destroyed, including birth certificates. Once the local government was up and running again, they were able to claim that their birth certificates had been among those destroyed and were supplied new ones, documents which also granted them American citizenship.

The Chinese population was not the only to see this as an opportunity. This idea of a phoenix-like recreation of the city from the ashes galvanized the population after the disaster. Many of the survivors, even as they stood in the wreck of their homes or businesses, began to plan for the future. They were able to do so with aid from Congress, which appropriated Federal funds for reconstruction and to reimburse for destroyed property. Insurance companies paid out between $250 and $300 million; twenty of the 137 firms involved went bankrupt from paying the claims.

One of the most important legacies of the 1906 Earthquake is its contributions to the geological sciences. Observations made during this quake were invaluable to the understanding of tectonics and mapping of quakes to determine their source.